Miscellaneous Topics

11.1. Miscellaneous Topics#

  • Topics

    • Counter

    • Sorting

      • natural sorting

      • operator

    • Decorators

    • Regular Expressions

11.1.1. Counter#

Python provides some specialized container data types. We have used defaultdict. Now we will learn about another useful collection called Counter. This collection takes in a list of elements and returns a dictionary with the element as keys and their counts as values.

from collections import Counter
my_list = ['apple', 'apple', 'banana', 'pineapple']
c = Counter(my_list)
>>> Counter({'apple': 2, 'banana': 1, 'pineapple': 1})

from collections import Counter

import random
random.seed(503)

two_dices = []
for _ in range(1000):
    dice1 = random.randint(1,6)
    dice2 = random.randint(1,6)
    two_dices.append(dice1+dice2)
c = Counter(two_dices)

11.1.2. Sorting#

itemgetter accesses elements using [].

import operator
x = ((1, 'a', 3.5), (3, 'Z', 90))
sorted(x, key=operator.itemgetter(2))

import operator
x = [
    {'name': 'student2', 'test1': '100', 'test2': '90','test3': '65', 'test4': '68', 'test5': '94'},
    {'name': 'student83', 'test1': '88', 'test2': '76', 'test3': '65', 'test4': '97', 'test5': '82'},
    {'name': 'student31', 'test1': '90', 'test2': '87', 'test3': '66', 'test4': '95', 'test5': '72'}]

sorted(x, key=operator.itemgetter('name'))
sorted(x, key=operator.itemgetter('test1'))

x = (
    (2, 2, 3),
    (2, 1, 3),
    (1, 10, 2),
)

sorted(x, key=lambda ele: (ele[0], ele[1]))

data = (
    ('AMD', 'Advanced Micro Devices, Inc.',
     '$120.88', '+4.27', '121,475,927'),
    ('AAPL', 'Apple Inc.', '$164.71', '+1.97', '80,725,613'),
    ('OPEN', 'Opendoor Technologies Inc', '$8.42', '-2.55', '53,559,847'),
    ('NVDA', 'NVIDIA Corporation', '$240.82', '+3.34', '49,046,544'),
    ('ZNGA', 'Zynga Inc.', '$9.18', '+0.37', '48,193,380'),
)
sorted(data, key=operator.itemgetter(3))

from natsort import natsorted
natsorted(data, key=lambda ele: ele[3], reverse=True)
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